A first purpose of the present invention consists in improving conventional working cylinders of the type herein discussed so that the sealing of the operating chamber is secure in a simple manner and independent from the quality and exactness of the manufactured components.
To attain this purpose, the invention provides that the envelope device which is constructed preferably as a rolling-bellow diaphragm is constructed as an envelope which is closed substantially on all sides and defines the operating chamber which receives the pressure medium.
Thus the envelope device can be constructed already during the manufacture process as a uniform, closed hollow member, which has the advantage that later seals or pressure-tight connections between the rigid parts are not needed. The envelope device can thereby be formed corresponding with the contour of the rigid parts and can be inserted in these and/or can be placed over same. The envelope device needs only still to be attached to the rigid parts, in order to secure it against a possible slipping.
In the preferred exemplary embodiments, an advantage results that a compact and small working cylinder is obtained.
The invention furthermore has the purpose to produce a modification in which the cylinder can be utilized as a double loadable working cylinder without a substantially more complicated structure. The pressure-tight separation is formed in this case in a simple manner by the elastic-deformable envelope device, which assures an absolute seal over a long period of time, because between the sealing envelope device and the rigid parts there does not take place substantially any relative movement which effects a drive. The envelope device is only rolled onto or from the respective sealing surface on the rigid part.